/*
 * Copyright 2018 The Error Prone Authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.errorprone.bugpatterns;

import com.google.errorprone.BugCheckerRefactoringTestHelper;
import com.google.errorprone.CompilationTestHelper;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.JUnit4;

/**
 * Tests for {@link BadInstanceof} bugpattern.
 *
 * @author ghm@google.com (Graeme Morgan)
 */
@RunWith(JUnit4.class)
public final class BadInstanceofTest {
  private final CompilationTestHelper compilationHelper =
      CompilationTestHelper.newInstance(BadInstanceof.class, getClass());

  private final BugCheckerRefactoringTestHelper refactoringHelper =
      BugCheckerRefactoringTestHelper.newInstance(BadInstanceof.class, getClass());

  @Test
  public void refactoring() {
    refactoringHelper
        .addInputLines(
            "Test.java",
            """
            class A {
              boolean foo(C c) {
                return c instanceof A;
              }

              boolean notFoo(C c) {
                return !(c instanceof A);
              }

              static class C extends A {}
            }
            """)
        .addOutputLines(
            "Test.java",
            """
            class A {
              boolean foo(C c) {
                return c != null;
              }

              boolean notFoo(C c) {
                return c == null;
              }

              static class C extends A {}
            }
            """)
        .doTest();
  }

  @Test
  public void positiveCases() {
    compilationHelper
        .addSourceLines(
            "Test.java",
"""
class A {
  // BUG: Diagnostic contains: `new C()` is a non-null instance of C which is a subtype of A
  boolean t = new C() instanceof A;

  boolean foo(C c) {
    // BUG: Diagnostic contains: `c` is an instance of C which is a subtype of A
    return c instanceof A;
  }

  boolean notFoo(C c) {
    // BUG: Diagnostic contains: `c` is an instance of C which is a subtype of A
    return !(c instanceof A);
  }
}

class C extends A {}
""")
        .doTest();
  }

  @Test
  public void negativeCases() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            class A {
              boolean foo(A a) {
                return a instanceof C;
              }
            }

            class C extends A {}
            """)
        .doTest();
  }

  @Test
  public void patternMatching_finding() {
    compilationHelper
        .addSourceLines(
            "Test.java",
            """
            class A {
              String foo(String s) {
                // BUG: Diagnostic contains:
                return s instanceof String x ? x : "null";
              }
            }
            """)
        .doTest();
  }

  @Test
  public void patternMatching_noFix() {
    refactoringHelper
        .addInputLines(
            "Test.java",
            """
            class A {
              String foo(String s) {
                return s instanceof String x ? x : "null";
              }
            }
            """)
        .expectUnchanged()
        .doTest();
  }
}
